Handheld device for measuring macular pigment

ABSTRACT

An instrument includes a housing with a lower hand-held portion having a user-input button and a display for displaying an MPOD score for the user. The instrument further includes a viewing tube coupled to the hand-held portion. The viewing tube terminates in an eye cup. The viewing tube is transverse to the lower hand-held portion and transmits light from a light source in a direction toward the macula. The light source is an LED and provides two colored lights alternating at an initial frequency that is not perceptible by the user. The frequency decreases from the initial frequency until the user activates the user-input button in response to a frequency at which the user perceives a flicker of the two colored lights. The frequency at the perceived flicker relates to the MPOD score of the user. The MPOD score correlates to the amount of macular pigment.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to U.S.Provisional Application No. 62/705,262, entitled “Handheld Device ForMeasuring Macular Pigment,” and filed on Jun. 18, 2020. The contents ofthat application are hereby incorporated by reference in their entirety.

FIELD OF INVENTION

The present invention relates to a handheld device that measurescharacteristics of the patient's eye, such as macular pigment, with ahigh degree of accuracy.

BACKGROUND OF THE INVENTION

The retina is the layer of nerve cells at the back of the eye, whichconvert light into nerve signals that are sent to the brain. In humans,and in other primates, the retina has a small yellowish area in thecenter of the field of vision. That yellowish area is called the“macula.” It provides fine-resolution vision in the center of the visualfield and is essential to good vision. People who suffer from maculardegeneration often lose the ability to read, recognize faces, drive, orwalk safely on unfamiliar routes.

“Retinal degeneration” is a descriptive term, which refers to an entireclass of eye diseases and disorders. It includes any progressivedisorder or disease that causes the macula to gradually degenerate, to apoint that substantially impairs or damages eyesight and vision. Severalmajor categories of retinal degeneration are known. These include: (i)age-related macular degeneration, which gradually appears among somepeople over the age of about 65; (ii) diabetic retinopathy, in whichproblems with sugar and energy metabolism damage the entire retina,including the macula; (iii) eye diseases that affect the macula due togene and/or enzyme defects, such as Stargardt's disease, Best's disease,Batten's disease, Sjogren-Larsson syndrome, and various other eyedisorders that lead to gradual degeneration of the macula (and possiblyother parts of the retina) over a span of time. This is not an exclusivelist, and other subclasses and categories also are known. For example,age-related macular degeneration is subdivided into wet and dry forms,depending on whether abnormal and disruptive blood vessel growth isoccurring in the structural layers behind the retina.

Awareness has grown of the roles that macular pigment plays in thehealth and longevity of the macula. Therefore, the two carotenoidpigments that create and provide the macular pigment are discussedbelow. The macula has a yellowish color because it contains unusuallyhigh concentrations of two specific pigments, called zeaxanthin andlutein. Both are carotenoids, similar to beta-carotene but with hydroxygroups coupled to their end rings (the presence of one or more oxygenatoms causes a carotenoid to be categorized as a “xanthophyll”, sozeaxanthin and lutein are sometimes referred to as xanthophylls). Bothof those two carotenoids are known to be protective and beneficial, inhuman retinas, by mechanisms that include: (1) absorption of destructiveultraviolet and blue light; and (2) quenching of destructive radicals.

Despite the rarity of zeaxanthin in food sources (zeaxanthin content intypical diets is believed to be less than about 1% of the luteinsupply), zeaxanthin concentrations in human blood average about 20% oflutein levels. This suggests the human body does something thatindicates a selective preference for zeaxanthin, over lutein. Further,zeaxanthin is even more concentrated in the important center of ahealthy human macula that provides fine-resolution vision in humans.There, zeaxanthin is present at levels that average more than twice theconcentrations of lutein. By contrast, lutein is present in higherlevels around the less-important periphery of the macula. The patternsof deposition suggest that the macula prefers zeaxanthin, and useslutein when it cannot get enough zeaxanthin.

The present invention provides a handheld device for measuring macularpigment that is light and portable and is easy to operate by the user.

SUMMARY OF THE INVENTION

In one embodiment, an instrument for determining macular pigment of amacula of a human eye includes a housing and a viewing tube. The housingincludes a lower hand-held portion with a user-input button and adisplay for displaying an MPOD score for the user. The lower hand-heldportion further includes a battery and electronics for operating theinstrument. The viewing tube is coupled to the hand-held portion andterminates in an eye cup. The viewing tube is transverse to the lowerhand-held portion and includes a light source for transmitting light ina direction toward the macula. The light source provides two coloredlights alternating at an initial frequency that is not perceptible bythe user, and the frequency decreases from the initial frequency untilthe user activates the user-input button in response to a frequency atwhich the user perceives a flicker of the two colored lights. Theperceived frequency is used for determining the MPOD score for the user.

According to one aspect of the invention, a handheld instrumentdetermines the macular pigment in the macula of a human eye. Theinstrument includes a housing including a lower hand-held portion and aviewing tube. The viewing tube is coupled to the hand-held portion andterminates in an eye cup. The viewing tube is transverse to the lowerhand-held portion and transmits light from a light source in a directiontoward the macula. In some embodiments, the viewing tube lacks anylenses between the light source and the eye cup. The instrument providesan MPOD (macular pigment optical density) score for the user thatcorrelates to the amount of macular pigment. The MPOD score correspondsto the density of the macular pigment in the retina.

According to another aspect of the invention, an instrument determinesthe macular pigment of a macula of a human eye. The instrument includesa housing with a lower hand-held portion having a user-input button anda display for displaying an MPOD score for the user. The instrumentfurther includes a viewing tube coupled to the hand-held portion. Theviewing tube terminates in an eye cup. The viewing tube is transverse tothe lower hand-held portion and transmits light from a light source in adirection toward the macula. The light source is an LED and provides twocolored lights alternating at an initial frequency that is notperceptible by the user. The frequency decreases from the initialfrequency until the user activates the user-input button in response toa frequency at which the user perceives a flicker of the two coloredlights. The frequency at the perceived flicker relates to the MPOD scoreof the user. The MPOD score correlates to the amount of macular pigment.

In another embodiment, an instrument for determining macular pigment ofa macula of a human eye comprises a housing a viewing tube. The housingincludes a lower hand-held portion. The lower hand-held portion has auser-input button and a display for displaying an MPOD score for theuser. The viewing tube is coupled to the hand-held portion andterminates in an eye cup. The viewing tube is transverse to the lowerhand-held portion and has a diameter between about 20 to 35 mm. Theviewing tube transmits light from a light source in a direction towardthe macula. The light source is an LED and provides two colored lightsalternating at an initial frequency that is not perceptible by the user.The frequency decreases from the initial frequency until the useractivates the user-input button in response to a frequency at which theuser perceives a flicker of the two colored lights. The frequency at theperceived flicker is related to the MPOD score of the user. The devicemay be used with a plurality of lenses, each of which can be fitted intothe viewing tube. The lens may be selected based on the state of theuser's eyesight.

Additional aspects of the invention will be apparent to those ofordinary skill in the art in view of the detailed description of variousembodiments, which is made with reference to the drawings, a briefdescription of which is provided below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an isometric view of the internal components of the handhelddevice for measuring macular pigment.

FIG. 1B is a side view of the internal components of the handheld devicefor measuring macular pigment.

FIG. 2 is an expanded view of the viewing tube barrel of the handhelddevice of FIGS. 1A and 1B.

FIG. 3 is an exemplary MPOD graph for a user.

FIG. 4A is an isometric view of the internal components of analternative handheld device for measuring macular pigment.

FIG. 4B is a side view of the internal components of the alternativehandheld device of FIG. 4A.

FIG. 4C is a side view of a pair of possible lends to be used with thehandheld device of FIGS. 4A and 4B.

While the invention is susceptible to various modifications andalternative forms, specific embodiments will be shown by way of examplein the drawings and will be described in detail herein. It should beunderstood, however, that the invention is not intended to be limited tothe particular forms disclosed. Rather, the invention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

The drawings will herein be described in detail with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to the embodiments illustrated. For purposes ofthe present detailed description, the singular includes the plural andvice versa (unless specifically disclaimed); the words “and” and “or”shall be both conjunctive and disjunctive; the word “all” means “any andall”; the word “any” means “any and all”; and the word “including” means“including without limitation.”

FIGS. 1A and 1B illustrate a handheld device 10 for measuring themacular pigment optical density (MPOD) of a user's macular. The device10 includes a handle 12 that is ergonomically shaped to be received bythe user's hand and a viewing tube 14 with a user input region having aneye cup 16 into which the user looks during operation. The axis of theviewing tube 14, which includes the primary optical components of thedevice 10, is generally perpendicular to the axis of the handle 12.

The handle 12 of the handheld device 10 serves as a housing for themicrocontroller 22 that is used for operating the various components andcontrolling multiple operations simultaneously. The microcontroller 22preferably has Wi-Fi functionality, Bluetooth functionality, andlow-power capabilities. The microcontroller 22 is mounted on a printedcircuit board with other components to perform the operations of thehandheld device 10. In one preferred embodiment, the microcontroller 22is a ESP32 chip (manufactured by Espressif).

The handle 12 also includes a button 24 that can be actuated by the userduring operation. The button 24 is coupled to the microcontroller 22 andis ergonomically located at a side of the handle 12 to allow the user toeasily actuate the button with his or her finger while holding thehandle 12. A display 26, which may be an OLED display, is positioned onthe handle 12 and is also coupled to the microcontroller 22, allows forthe display of various pieces of information to the user regarding theoperation of the handheld device 10. The handle 12 incudes the battery28 needed for operating the entire device 10. For charging the battery28, the handheld device 10 can be coupled to a separate base dockingstation or attached to a wire charger. In one embodiment, the battery 28is preferably a 2200 mAh battery with a voltage regulator that isincluded in the circuit to boost the battery from 3.3 Volt to 5 Volt.The battery 28 can power MPOD device 10 for a period of several days ona single charge.

FIG. 2 illustrates the viewing tube 14 in more detail. Within theviewing tube 14 of the handheld device 10, there are two different sizedapertures—a light ring 32 and an aperture 34 in a blocking wall 33—tohelp the user focus on a light source 30 situated at the rear of theviewing tube 14. The light source 30 is mounted co-linearly along thecenter axis of the viewing tube 14 to provide a fixation target for theuser. The light ring 32 provides a light-colored (preferably white)background with an inner circular opening through which the uservisualizes the light source 30, thereby providing proper contrast to thelight source 30.

The light source 30 is preferably a red-green-blue (RGB) LED situated atthe rear of the viewing tube 14. The light ring 32 is used to helpilluminate the aperture 34 in the blocking wall 33 giving a white wallwith the blue/green light source 30 in the center. The front wall of theaperture 34 is preferably a white color. The backside of the light ring32 facing the light source 30 is also preferably a white wall. The frontside of the light ring 32, which faces the user, is preferably a darkcolor. The light source 30 transmits the input light through theaperture 34, which is adjacent thereto, and through the light ring 32where it enters the user's eye via the eye cup 16. The operation of thedevice 10 with the blue and green lights is discussed further below. Thered light can be used to alert the user that the test is completed.

The overall inner diameter of the viewing tube 14 is in the range fromabout 20 to 35 mm, and is preferably about 28 mm in diameter. The LEDlight source 30 transmits light at an angle of about 1 degree. Theaperture 34 preferably has a diameter of about 1.5 mm, while the openingin the light ring 32 has a diameter of about 10 mm. The spacing betweenthe light source 30 and the aperture 34 is about 2 mm. The spacingbetween the light ring 32 and the blocking wall 33 defining the aperture34 is typically from about 10 mm to about 50 mm. In one embodiment, thespacing between the light ring 32 and the blocking wall 33 defining theaperture 34 is about 25 mm. The spacing between the light ring 32 andthe eye cup 16 is in the range of about 20 mm to 60 mm, which isdetermined by whether a magnification lens is used and, if so, the powerof the magnification. In one embodiment, the ratio of the diameter ofthe opening in the light ring 32 to the distance between the light ring32 and the eye cup 16 is about 1:2. Consequently, the user's eye is at aknown distance from the LED light source 30 and the background adjacentto the light transmitted from the light source 30 within the user'svision is known.

In one embodiment, the device 10 provides a benefit over known devicesbecause there are no lenses in the optical path between the light source30 and the user's eye. Rather, the user only visualizes the light sourcethrough the openings in the light ring 32 and the aperture 34. The endof the viewing tube 14 may have a piece of glass or plastic so as toseal the inner region of the viewing tube 14 adjacent to the eye cup 16.

Alternatively, the viewing tube 14 may include a lens as the sealingcomponent near the eye cup 16. The lens may assist the user in viewingthe light from the light source 30. As discussed in more below withrespect to FIG. 4C, the lens may be, for example, between 10-15diopters. On other embodiments, the lens is from about 5-10 diopters. Ina further embodiment, the device 10 may include a kit of barrelextenders that extend the length of the viewing tube 14, with eachbarrel extender provider a different lens to assist the users withspecific lens needs in viewing the light from the light source 30. Forexample, the lens available in the kit of barrel extenders may be 1diopter, 3 diopters, and 5 diopters, and each barrel extender may be ofa certain length. Each barrel extender may be fastened to the viewingtube 14 via clips or threads.

The handheld device 10 can help track the progression of maculardegeneration via MPOD scores. This device 10 is designed to be portable,easy to use, and provide accurate diagnostics. When the device 10 isoperated, the display 26 mounted on the handle 12 of the device 10provides information (alpha-numeric data and graphics) to instruct theuser on how to begin the MPOD test and informs the user which eye willbe tested. The display 26 instructs the user to place his or her eyeonto the eye cup 16 and the testing begins. The display 26 is preferablyan OLED display device.

At the start of the test, the LED light source 30 alternates betweengreen and blue light beginning at a frequency of about 60 Hz, which isimperceptible to the user. In other words, the user perceives a constant(non-flickering) blueish-green light. The frequency of the LED lightsource 30 then decreases until the user can see a flickering effectcaused by the alternating colors of green and blue. The user input plusa defined offset (e.g., about 6 Hz) is saved as the new initialfrequency for the starting point for the main testing procedure for theuser. The defined offset ensures the test starts above the user'sperception of flickering, while not wasting testing time as thefrequency decreases from a much high frequency. This first step servesto save time in the test procedure. The main test then proceeds andrecords the user's starting point for the main testing procedure.

For the subsequent tests, the device 10 now changes the decibel ratiobetween the blue and green LED intensities by 0.2 decibels. The bluelight may be decreased while the green light is increased to keep theoverall intensity about the same. Using the initial frequency as the newstarting frequency, the device 10 begins to reduce by 3-6 Hz per second.When the user sees an observable flicker, he or she presses on thebutton 24 located on the side of the handle 12 of the device 10, whichindicates to the device 10 that the user has perceived the flicker.Again, the starting frequency is changed based on the user's previousinput. The device 10 changes the decibel ratio and begins the test againuntil a local minimum is discovered in their curve of dB ratio versusfrequency graph.

At this point, the test is completed and the MPOD score is calculatedand displayed on the OLED display 26. A user's MPOD score is based onhow their eye reacts to the flickering that is perceived. A healthy eyewill have a minimum frequency value at much higher decibels, as seen asfarther right on FIG. 3 . In FIG. 3 , the minimum value of about 24 Hzis at about 7 decibels. A healthier eye will respond faster to theflicker. These two inputs are used to determine the overall health of apatient's macula. The user is then instructed by the display 26 to usethe device 10 on the user's other eye or it will automatically go tosleep due to inactivity.

The user's MPOD score can be stored locally on memory within the device10. By use of the Wi-Fi and/or Bluetooth communications capability ofthe microcontroller 22, the MPOD measurements from the device 10 can betransferred to the user's personal mobile phone or device, local storage(e.g., a computer), or cloud storage associated with the user and/orfacility that owns the device 10. Preferably, the device 10 can streamthe MPOD scores to the cloud for immediate review by a doctor.

Preferably, the device 10 that adapts in real time to the speed of theuser's input. If the user is not able to perceive the flicker at highfrequencies the device 10 will automatically start each test at lowerfrequencies to save time during the overall test, as noted above.

The alternating blue-green flicker (other colors of flicker can be usedas well) is selected such that there is no temporal overlap between thedifferent colored lights. Alternatively, there can be some overlapbetween the blue light and green light during the flicker, which canprovide the benefit of a more consistent luminosity. This also providesa benefit with a smooth transition during ramp up and ramp down of theLEDs.

The device 10 may also include an age-correction function into thisdevice. As a user ages, their MPOD score will predictably shift down thegraph of FIG. 3 . Therefore, two individuals with the same MPOD scorecan have completely different diagnoses. To compensate for the user'sage, the device 10 may allow users to input their age.

In another preferred embodiment, the device 10 includes a camera andlens system directly adjacent to the light source 30. The cameraprovides the ability to take images of the user's retina and macula asthe user is engaged in the MPOD test with the device 10. The images canbe stored locally and/or transferred from the device 10.

FIGS. 4A and 4B illustrate an alternative MPOD device 110 relative tothe MPOD device 10 of FIGS. 1-2 . In FIGS. 4A-4B, the reference numeralsare listed as 100-series reference numerals that represent structuresand features that are similar to the structures and features of thedevice 10 of FIGS. 1-2 that have two-digit reference numerals. The MPODdevice 110 includes a handle 112 and a viewing tube 114. Unlike thedevice 10 of FIGS. 1-2 , the viewing tube 114 flares outwardly,preferably at an angle of less than 10 degrees. In one embodiment, theflare angle of the viewing tube 114 is about 3 degrees.

The handle 112 includes a button 124 that can be actuated by the userduring operation. The button 124 is coupled to a microcontroller (notshown in FIGS. 4A-4B) and is ergonomically located at a side of thehandle 112 to allow the user to easily actuate the button 124 with hisor her finger while holding the handle 112. A display 126, which may bean OLED display, is positioned on the handle 112 to permit thecommunication of various pieces of information to the user regarding theoperation of the MPOD device 110. Unlike FIGS. 1-2 , the handle 112incudes a battery 128 at the lowermost portion of the handle 112, whichallows the user to hold the device 110 with more stability because theweight of the battery 128 is shifted to a location where the user gripsthe handle 112. In one embodiment, the battery 128 can power the MPODdevice 110 for a period of several days on a single charge.

In the MPOD device 110, the LED light source 130 in the viewing tube 114is shifted further away from the eyecup 116. To help the user focus on alight source 130 situated at the rear of the viewing tube 114, there area pair of light rings 132 a and 132 b to provide a light-coloredbackground with inner circular openings through which the uservisualizes the light source 130, thereby providing proper contrast tothe light source 130. The front side of the light ring 132 a, whichfaces the user, is preferably a dark color. A blocking wall 133 with anaperture 134 is located directly in front of the light source 130 in thecenter of the viewing tube 114. The light source 130 transmits the inputlight through the aperture 134, which is adjacent thereto, and throughthe light rings 132 a and 132 b where it enters the user's eye via theeye cup 116. The operation of the device 110 is preferably with the blueand green lights, as discussed above.

The MPOD device 110 also provides the user with the option for tactilefeedback or audio feedback. At the lower portion of the handle 112, amotor 142 creates a vibratory feedback to let the user know that thespecific test or test sequence is about to start or is finished. Thevibratory feedback from the motor 142 may also be used to inform theuser that the user's input via the button 124 has been received.Alternatively, or in addition to the motor 142, the MPOD device 110 mayinclude a speaker 144 to provide audio outputs to the user. The speaker144 can be used to provide instructions to the user on the operation ofthe overall (e.g., a tutorial on how the MPOD device 110 operates) or onparticular actions needed by the user (e.g., instructing the user toactuate the button 124 when the flicker becomes visible). The speaker144 can also inform the user if he or she is using the device 110correctly, or if there is too much shaking or movement of the device 110(e.g., by use of an internal accelerometer) during operation. In short,like a lighting sequence (e.g. blinking red light) from the LED device120, the motor 142 and the speaker 144 provide other ways to communicatewith the user.

The viewing tube 114 of the MPOD device 110 further includes a slot 150at a known position along the length of the viewing tube 114. The slot150 leads into a lower groove 152. The slot 150 and the groove 152 arefor receiving a lens, such as the lens 160 of FIG. 4C. In oneembodiment, the lens 160 is fitted within the slot 150 with its lowerend resting in the lower groove 152 of the viewing tube 114. The lens160 is permanently positioned fixed within the viewing tube 114.Alternatively, a kit of available lenses 160 and 162 is used with thedevice 110 and a lens is selected from the kit that works best for theuser. The lenses 160, 162 may be, for example, between 10-15 diopters.In other embodiments, the lens 160, 162 are between 5-10 diopters. In afurther embodiment, the standard lens 160 used with the device 110 isabout 13 diopters, and other lenses 162 in the kit provide values of 12diopters, 12.5 diopters, 13.5 diopters, and 14 diopters. The cliniciancan select from these other lenses to best work with the user.

Each of these embodiments and obvious variations thereof is contemplatedas falling within the spirit and scope of the claimed invention, whichis set forth in the following claims. Moreover, the present conceptsexpressly include any and all combinations and subcombinations of thepreceding elements and aspects.

What is claimed is:
 1. An instrument for determining macular pigment ofa macula of an eye of a user, comprising: a housing including a lowerhand-held portion with a user-input button configured for actuation bythe user and a display for displaying an MPOD score for the user, thelower hand-held portion further including a battery and electronics foroperating the instrument; and a viewing tube coupled to the hand-heldportion and terminating in an eye cup configured to be placed over theeye of the user, the viewing tube being transverse to the lowerhand-held portion, the viewing tube including a light source fortransmitting light and a blocking wall with an aperture adjacent to thelight source, the viewing tube further including a light ring with acenter opening, the light ring being located between the blocking walland the eye cup, the light source is located in the viewing tube suchthat the light is transmitted through the aperture of the blocking wall,through the center opening of the light ring, and toward the eye cup,the light source providing two colored lights alternating at an initialfrequency that is not perceptible by the user, the frequency decreasingfrom the initial frequency until the user activates the user-inputbutton in response to a frequency at which the user perceives a flickerof the two colored lights, the perceived frequency being used to fordetermining the MPOD score for the user.
 2. The instrument of claim 1,wherein the aperture of the blocking wall is about 2 mm away from thelight source.
 3. The instrument of claim 1, wherein a diameter of theviewing tube is in a range from 20 mm to 35 mm.
 4. The instrument ofclaim 1, further including a tactile-feedback device or anaudio-feedback device that is actuated in response to the useractivating the user-input button.
 5. The instrument of claim 1, whereinthe two colored lights are a blue light and a green light, the bluelight and the green light are generally in opposite on-off phases withsome overlap at a transition between the phases.
 6. The instrument ofclaim 5, wherein the light source is a multi-colored LED.
 7. Theinstrument of claim 1, wherein the viewing tube includes a slot intowhich a lens can inserted.
 8. The instrument of claim 7, wherein thelens is selected for the user from a kit of lenses having diopter valuesbetween 10-15.
 9. The instrument of claim 1, wherein the viewing tube isgenerally perpendicular to the lower hand-held portion.
 10. Theinstrument of claim 1, further including a battery located at alowermost portion of the lower hand-held portion for providing morestability of the instrument when being held by the user.
 11. Theinstrument of claim 1, wherein a front surface of the blocking wallfacing the eyecup is lighter colored, and a front surface of the lightring facing the eyecup is darker colored.
 12. The instrument of claim 1,wherein a front surface of the blocking wall facing the eyecup is white.13. The instrument of claim 1, wherein the light ring emits light of adifferent color than the two colored lights of the light source.
 14. Theinstrument of claim 13, wherein the light ring illuminates the blockingwall.
 15. The instrument of claim 14, wherein the light ring emits whitelight.
 16. The instrument of claim 14, wherein a front surface of thelight ring facing the eyecup is darker colored.
 17. The instrument ofclaim 1, wherein the light source transmits the light directly towardsthe aperture in the blocking wall.
 18. The instrument of claim 17,wherein the light source is mounted along a center axis of the viewingtube.
 19. The instrument of claim 1, wherein the light source is locatedat the rear of the viewing tube and spaced away from the blocking wall.20. The instrument of claim 1, wherein the light source is mounted onthe blocking wall.